Journal Club

October 17, 2013

Russell Quapp, PGY-4

Incidence reports vary widely:6.6 – 90%21-65%53 – 57% with double lumen tubes25 – 57%100% ....

The post-operative sore throat

Etiology:We stick something into peoples’ tracheas that

don’t belong there....

Risk factors

Preventative measuresNon-pharmacologicPharmacologic

The post-operative sore throat (POST)

Anesthesia and Analgesia; 2009. 40 patients in two groups.

Why might licorice work?

Many active ingredients:Glycyrrhizin – anti-inflammatory/anti-allergic

propertiesGlycyrrhizic acid – inhibits COX activity, PG

formation, platelet aggregationLiquilitin, Liquiritigenin glabridin – antitussives

(peripherally/centrally)Hispaglabridins – antioxidant/ulcer healing

properties

Why might licorice work?

Figure 1

Surgery size:

Small (thoracoscopy)

Medium (thoracotomy <3h)

Large (thoractomy >3h or blood loss >1000mL)

Patient Demographics

Premedicated with oral midazolam (up to 7.5 mg)Randomized:

Licorice extract Sugar solution

Gargle for at least one minute sitting Induction five minutes post gargling (fentanyl, propofol,

rocuronium) Intubation following loss of TOF with DL ETT

(*unlubricated) with cuff pressures of 20 mmHg Intra-operative analgesia with narcotics/paracetamol and a

intercostal plexus block at the end of surgeryExtubated “while still anesthetized”Post-operative analgesia with piritramide (synthetic opioid

slightly weaker than morphine)

Protocol

Measurements were taken at 30 minutes, 90 minutes after arrival in PACU and 4 hours post extubation11 point Likert scale (0 – 10)

Also assessed pain on swallowing at 30 minutes.Any score >0 defined as a sore throat.Coughing assessed by observation and questioning

the patient at 0, 30, 90 minutes post extubation.None = 1Mild = 2Moderate = 3 (similar to common cold)Severe = 4

Above measures repeated on first morning post-op.

Measurement

Interim AnalysisEfficacy

Futility

Harm

Primary outcome:Effect of licorice gargle on occurrence of sore

throat at rest after intubation with DL ETT compared with sugar-water through the first four postextubation hours.

Secondary outcomes:Effect of licorice on sore throat on

postoperative day 1Incidence of sore throat during swallowing

assessed at 0.5 hours post PACU arrivalIncidence of coughing over 5 time

measurementsAmount of coughing over 5 time measurements

Outcomes

Analysis Measurements

Results

Statistical black box of number crunching

Overall RR = 0.46 (0.29-0.72)

Results

Results

Validity - Sniff test?Seems to be okay – particularly for the

primary outcome.Do I care particularly about coughing end

points?Decreased coughing would likely be decreased

pain in the post-thoractomy patient.

Primary assess effect of licorice gargle on sore throat at

rest after intubation with DL ETT compared with sugar water at 0.5, 1.5, 4 hours.

SecondarySore throat at rest POD 1Incidence of sore throat during swallowing at

0.5 hoursOverall difference in pain scores between at

rest and swallowing at 0.5 hours and across four time points.

Incidence of coughing and amount/severity of coughing

Validity – Clearly defined outcomes?

Pain vs. No painObjective outcome

Amount of pain (0-10)More subjective, but validated scale

Incidence of coughingObjective

Amount of coughingVery subjective.? Validated (was published previously)

Validity – Measurements

Validity - Randomization?“Web-based” system used just prior to

procedure.Don’t state what system in particular was

used…

Validity - Randomization – groups similar?

>0.2 standardized difference would indicate imbalance

Validity - Blinding?Randomization with computerized system by

“independent researcher” not involved in subsequent data collection

Licorice/sugar preparations by “independent apothecary”

Independent researcher not involved in data collection used to supervise gargling

Patients not told which solution they were usingThough likely could tasteWere only told they would be trying two

different “sweet” solutions

Validity - Blinding?Assessments in PACU were done by nurses

“not present” for garglingPossible patient’s could mention what flavor

they had when gargling….Post-operative assessment on day 1 done by

“independent and blinded investigator”Again, possible that patient could mention/tell

investigator what they had tasted

Validity - Intention to treat/loss to follow up?One patient in each arm was lost to follow-up

Both remained intubated post surgeryLicorice group

Results were entered as “worst case scenario”i.e. sore throat at all time points, coughing at

all time pointsSugar group

Results entered as “best case scenario”i.e. no sore throat at any time point and no

coughing at any time pointAlso one patient withdrawn secondary to

emergency surgery

Validity - Similar to our patient population?

Looks similar

DL ETT vs. Single lumen ETTIncidence with DL ETT likely higherWould relative risk/treatment effect be as

pronounced with single lumen tubes?Previous study was with single lumen tubes

Thoracic/Thoracotomy patientsNo documentation of comparability of opioids

administered during cases.Hopefully similar between groups

No documentation regarding airway grading/difficulty

Use of dexamethasone?

Limitations/Weaknesses

Why bother with the safety analysis?

Given the low pain scores in their study, how important a complication is it?

Limitations/Weaknesses

Two studies now showing nearly identical results2 fold decrease in incidence of post-operative

sore throatStatistically significant resultsShould this change my practice?

How much do I care about POSTIncidence seems relatively highBut how bad is it (very low pain scores in this

study)Is there any monetary cost (work days lost,

prolonged hospital stay etc.) associated with POST

Doesn’t appear to be any harm, likely very inexpensive, potential benefit...

What about LMA’s?

Will this change my practice?